A core charge is added to your total. In this case, you would send your transmission back as a "core" for a refund for the core charge. You do not have to send your core back but it is encouraged. If you choose not to, then you will not be refunded your core charge. Below is a little more information about returning cores.
Core credit returns will be accepted within 180 days of original purchase. After 180 day core credit refunds will be at the discretion of XDP.
To return your product core for credit, first drain all fluids, if any, from the product. Then fill out the Return Form (LOCATED HERE). XDP will email you with an RMA number and detailed return instructions. Please wait for shipment instructions before shipping any cores, many cores will be sent directly to the manufacturer.
XDP recommends using a carrier that provides package tracking to ensure your product gets back safely and quickly. You will not be reimbursed for shipping costs incurred in shipping the core.
The credit card used for the purchase of the product giving rise to the core return will be credited with the core's original invoiced value after inspection.
Cores that have been disassembled or have missing and/or damaged major components will not receive full core credit.